Shape memory effects of molded flexible polyurethane foam

Abstract

Polyurethane flexible foam having shape memory effects has been synthesized from polyester polyol and 4,4′-diphenylmethane diisocyanate (MDI) following the quasi-prepolymer method in the presence of water as the blowing agent, and the effect of the organometallic catalyst and the molecular weight of polyol has been studied. It was found that the closed cell content, foam density, rubbery modulus, compression set, and shape fixability increased with increasing amounts of organometallic catalyst and decreasing molecular weight of polyol, whereas the cell size showed the opposite tendency. On the other hand, the shape recoverability of the foam was over 99% regardless of the catalyst content and molecular weight of polyol.

Shape memory polyurethane foams

“…Figure 6 shows the cyclic loading and unloading behavior of the foam for the first four thermomechanical cycles. It is seen that the shape fixity decreases from about 84 (S10) to 72% (S06) while shape recovery increases from 52 (S10) to 63 % (S06) with increasing molecular weight and functionality of the polyol [27]. This indicates that shape fixity depends on the glassy state modulus and shape recovery on the rubbery state modulus.…”

“…Consequently, the basic structure-property relationships of the shape memory foam have not been reported perhaps except those by the present groups [26,27]. In this work molded flexible polyurethane foams have been synthesized from polypropylene glycol (PPG) with various molecular weights (M w ) and functionalities (f), and 2,4/2,6-toluene diisocyanate with water as blowing agent.…”

Preparation and Characterization of Shape Memory Polymer Scaffolds via Solvent Casting/Particulate Leaching

“…Namely, the study on SMP foams has been originally proposed by Hayashi and Sokolowski (10,(32)(33)(34), and their applications in medical devices by the latter in cooperation with Prof. Yahia (8)(9)(10)35). Moreover, it has been shown that polyurethane flexible foams with tunable shape fixability and cell size can be obtained without any major effects on shape recoverability (36). However, for such a class of SMP polyurethane-based foams, the foaming is in general obtained during polyurethane synthesis (i.e.…”

Porous Shape-Memory Polymers

“…Multiple studies report foaming in polyurethane SMPs by chemical blowing processes, such as those in which CO 2 is generated by adding water to isocyanate-containing premixes during curing. [18, 19] …”

“…[35, 58-60] Chung and Park fabricated polyurethane SMP foams from a segmented thermoplastic polyurethane using salt leaching, [27] and Chung, Kang, and co-workers also fabricated an electrospun web using the same thermoplastic polyurethane. [61] Domeier [62] and Lee [19] also studied polyurethane based SMP foams (Table 1). …”